polarssl_cert_req: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/polarssl_cert_req - from package: libpolarssl-runtime

You may install the required package with command apt-get install {package}

Error in other languages:
polarssl_cert_req: bevel nie gevind nie
polarssl_cert_req: comandă negăsită
polarssl_cert_req: comando não encontrado
polarssl_cert_req: commande introuvable
polarssl_cert_req: command not found
polarssl_cert_req: käsku ei ole
polarssl_cert_req: không tìm thấy lệnh
polarssl_cert_req: komanda nerasta
polarssl_cert_req: Kommando nicht gefunden.
polarssl_cert_req: kommandot finns inte
polarssl_cert_req: komut yok
polarssl_cert_req: nie znaleziono polecenia
polarssl_cert_req: níor aimsíodh an t-ordú
polarssl_cert_req: no se encontró la orden
polarssl_cert_req: no s'ha trobat l'ordre
polarssl_cert_req: opdracht niet gevonden
polarssl_cert_req: parancs nem található
polarssl_cert_req: perintah tidak ditemukan
polarssl_cert_req: príkaz nenájdený
polarssl_cert_req: příkaz nenalezen
polarssl_cert_req: команда не найдена
polarssl_cert_req: командата не е открита
polarssl_cert_req: 命令找不到
polarssl_cert_req: コマンドが見つかりません